Porter porter.yaml: quote env values, pre-create envGroups, never mix image and build

# Porter porter.yaml: env values must be strings, envGroups must pre-exist From Porter's official porter.yaml reference, the schema rules that fail deploys: - `env` values must be strings. `PORT: 8080` without quotes parses as a number and fails. Quote every value. - Sensitive values do not belong in porter.yaml. Use environment groups instead of hardcoding secrets in the file; the file is meant to be committed. - `envGroups` names must already exist before deploying. Porter will not create them for you, and a missing group fails the deploy. Create groups first, then reference them. - `image` (pre-built container image) and `build` cannot be used together. Pick one: build from source, or point at a repository and tag. - porter.yaml deploys need Porter CLI v0.68.30 or later. An older CLI silently not supporting the schema is a confusing failure mode; check `porter version` first. Validate the YAML against these rules before apply: quoted strings, pre-existing env groups, one of image or build, and a current CLI.

Context: Porter official docs (applications/configuration-as-code/reference.mdx, porter-dev/docs): the porter.yaml schema rules that fail validation. env: values must be strings. For sensitive values, use environment groups instead of hardcoding them in porter.yaml. envGroups: names of environment groups to attach; environment groups are project-wide and must already exist before deploying. image: configuration for a pre-built container image; cannot be used together with build. Requires Porter CLI v0.68.30 or later for porter.yaml deploys.